The shell of a whole egg provides an effective package that protects the egg contents against contaminants from the environment and other sources. Integrity of the shell is critical for egg quality and safety. Shell cracks or imperfections permit ingress of bacteria that often grow rapidly when they migrate to the egg yolk. Growth of bacteria in egg contents leads to spoilage and increased risk of disease transmission. Egg shells are, however, inherently brittle; consequently, eggs are subject to unintentional cracking during laying, processing (including washing, rapid cooling, sanitization, and pasteurization), packing, shipping, stocking and handling by the end user. Mechanical handling during these operations further increases the potential for egg cracking. Pasteurization processes that rely on heat or heat combined with chemical treatments (e.g., heat-ozone combination) can weaken the egg shell and increase its tendency to shatter.
Upon detection (usually before packing and shipping), cracked eggs (known as “checks”) are diverted away from the retail market. However, eggs with weak shells are not detected by crack-checking devices, and may find their way onto supermarket shelves. These eggs tend to crack during routine shipping, stocking, or handling by the end purchaser. Furthermore, eggs having weak shells tend to shatter during use, often disrupting the yolk and mixing it with the albumen, or leaving shell fragments in egg contents. Shell weakness is disadvantageous, as it requires that the egg is cracked in a controlled manner so that the egg contents are preserved intact, if desired, during use. Therefore, methods and formulations which improve the strength of egg shells without adverse effect on their positive characteristics would be beneficial to the egg industry as well as consumers.